An RFID tag antenna is the most changeable part in an RFID system, and its design is faced with actual requirements of miniaturization, conformation, low cost and low loss, thus the optimal design of the RFID tag antenna is important in the whole RFID system.
At present, bandwidths of RFID tag antennas used by various systems are inconsistent with each other in the high-frequency ranges thereof. For example, a band of 866˜868 MHz is employed in the European, and a band of 902˜928 MHz is employed in the United States. When the RFID tag antenna is switched between the different bandwidths in different regions, the conventional RFID tag antenna is very difficult to be identified in the regions having different bandwidths due to bandwidth limitations. Moreover, when a dielectric thickness is less than 1 mm or a resonant frequency is lower than 910 MHz, a reading distance of the conventional RFID tag antenna is significantly poor. In order to achieve a good identification effect, it is necessary to increase the thickness, the length and the width of the conventional RFID tag antenna, which results that an outline dimension of the RFID tag antenna is increased and costs are increased accordingly.
Referring to FIG. 1, in the related art, many anti-metal tag antennas 10 of a high frequency have a micro strip antenna structure. In order to realize miniaturization, a radiation plate 3 and a ground plate 4 of the micro strip antenna are respectively disposed on a upper surface and a lower surface of a substrate 2, and thus a short-circuit pin 5 is needed to be provided between the radiation plate 3 and the ground plate 4. According to the conventional art, the short-circuit pin 5 between the radiation plate 3 and the ground plate 4 is implemented by printing or forming a via hole in general. For example, silver paste is printed on a ceramic surface; the via hole is formed on a PCB and then copper is deposited in or gold is plated in the via hole to connect the radiation plate 3 and the ground plate 4, and so on.
Since the above process for forming the short-circuit pin cannot be performed at the same time with the previous formation of the ceramic material or the PCB, the short circuit pin 5 has to be formed in a subsequent process. It causes problems such as decreasing productivity and rising cost. For example, the ceramic surface printing is often performed manually, but the labor cost is high and it is limited to the ceramic surface. Although the process of forming the via hole on the PCB is mature and suitable for mass production, it is not suitable for non-PCB materials due to large limitation of the PCB materials; additionally, the performance of the via hole short circuit is slightly less than that of the micro strip line short circuit.
In view of the above, there is a need in the art for a production process of a tag antenna with simplified process and reduced cost, and a novel small-sized RFID tag antenna, which has compatible functions and is remotely identifiable, becomes the direction of product development in the industry.